Gage for measuring length of flexible extrusions

ABSTRACT

A roller measurement fixture is comprised of a series of small in-line rollers mounted in one or more rows, forming a receiving cradle device. An extruded part to be measured is cradled in a semi-circular arrangement of the rollers and straightens as it settles under its own weight. The cradle device will accommodate many different cross-sections of extruded seal. The rollers are free to rotate as the part is placed into the fixture and properly located. Friction front these rollers is negligible, therefore the part remains in, or attains, its free state, without internal stresses, throughout the loading and measurement process. Thus, the extruded part is limp within the cradle, being loaded so as to contact a head or alignment stop at one end of the cradle. A floating stop riding on the rollers engages the other end of the part and cooperates with a scale on the cradle as a means of acquiring the measurements.

BACKGROUND OF THE INVENTION

Accurate length measurements of extruded rubber seals are required forproduction control data collection, capability studies, and shrinkagestudies. These seals are long flexible extruded parts having a varietyof crosssectional configurations, generally in length up to twenty feetor more. After extrusion, the seals are placed onto a measurementfixture, and an overall length measurement is recorded.

One of the problems with accurately measuring the overall length of suchextruded rubber seals is the variation caused by handling the part.Typically, one end of a long part is placed against an end stop in themeasurement fixture (such as an aluminum angle or channel, or on a flatwooden boundary board with attached scale) and straightened to extend toits full length where a measurement is recorded. Errors in lengthmeasurement will occur if the part is not perfectly straight on thefixture.

Another major contributor to errors in measurement is the stretching orcompressing (stuffing) of the extruded part while placing it into themeasurement fixture. This can create localized tension or compressionforces in the extrusion. The coefficient of friction between the typicalmeasurement fixture and the various rubber compounds is high enough toallow a stretched or stuffed part to remain in that altered state, e.g.such localized forces are not dissipated, while the part is beingmeasured. If a part is not in its "free state" (not stretched orstuffed) when measured, variations and measurement errors will result.

SUMMARY OF THE INVENTION

A novel roller measurement fixture has been designed, according to theinvention, to help eliminate both of the problems mentioned above. Thefixture is composed of a series of small in-line rollers mounted in oneor more rows, forming a receiving cradle device, such that the extrudedpart to be measured is cradled in a semi-circular arrangement andstraightened as it settles under its own weight. The semi-circularcradle device will accommodate many different cross-sections of extrudedseal. The fixture also contains a stainless steel scale that is used asa means of acquiring the measurements.

The cradle is preferably comprised of a series of rows of in-linerollers which are free to rotate as the part is placed into the fixtureand properly located. The friction from these rollers is negligible,therefore the part remains in, or attains, its free state, withoutinternal stresses, throughout the loading and measurement process. Thus,it can be characterized that the extruded part is limp within thecradle, being loaded so as to contact a head or alignment stop at oneend of the cradle.

A floating end stop with an integral pointer rides in or along the partcradle, and is used to rest against the free end of the part to indicatethe measurement on the scale attached to the fixture cradle.

The primary object of the invention, therefore, is to provide a methodand apparatus by which the length of long flexible extruded parts can bemeasured accurately by first supporting the part at a large number ofincremental locations along its length, each support being movablerelative to the adjacent surfaces of the part so as to allow the part tostraighten and to relax and dissipate any localized tension orcompression forces in the part prior to taking the length measurement.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are schematic diagrams of prior art measurement devices;

FIG. 3 is an end view of the measuring device, typically installed atthe delivery end of an extrusion apparatus;

FIG. 4 is an enlarged and broken partial front view of the cradle;

FIG. 5 is an enlarged cross-sectional view of the cradle and therollers, taken along line 6--6 in FIG. 5;

FIG. 6 is a plan view of the floating end stop; and

FIG. 7 is an end view of the floating end stop.

DESCRIPTION OF THE PREFERRED

FIG. 1 illustrates schematically the prior manner of measuring longflexible rubber (or the like) extrusions. Of particular interest aresynthetic material extrusions used for weather stripping and sealing inautomotive applications, such as around windows, in windows runs orchannels, and around doors and trunk lids. These seals are extrudedthrough a die to achieve the desired crosssectional configuration, whichis usually irregular, and cut to prescribed length.

Inspection of these extruded parts, particularly length measurement, isrequired to maintain uniformity and quality. Proper length is needed toavoid problems of installation on production lines. Both short and longextrusions present difficulties to the installer, who is working undertime constraint. The cut parts E (lengths) are placed on a flat board 10(FIGS. 1 and 2), one end against a stop 11, and the length is noted on arule 12 attached to the board. These parts are flexible and relativelysmall in cross-section and comparably quite long; for example, aparticular extruded seal might be 1.5 inches across its greatestcross-section, up to twenty feet or more in length. The material isoften sponge-like and in any event is easily subject to localizedcompression or tension as the part is manually laid out on board 10.

The coefficient of friction between the part and the board can result ininternal localized stress (either compression or tension) which affectsthe true length (when relaxed) of the part. Also, the part may be(hurriedly) not laid in a straight line, as illustrated in anexaggerated way in FIG. 2. All of these variations, caused in part byhaste during the manufacturing operation, may result in parts ofincorrect length measurement.

In accordance with the invention, a novel roller measurement fixture isprovided to help eliminate both of the problems mentioned above. Thefixture is comprised of a series of small in-line rollers 20 supportedon small shafts 22 aligned in one or more rows 20A, 20B, 20C, within atrough 25 which is an open beam 26 having legs 27A, 27B preferably atright angles to each other, with a small shelf 28 secured across itsbottom, at the joinder of the legs 27A, 27B forming a receiving cradledevice. The cradle is preferably comprised of the three (or more) rows20A, 20B, 20C of in-line rollers 20 each of which are free to rotate ontheir respective support shafts 22 as the part is placed into thefixture through its open top and properly located. The shafts are allmounted to extend transverse to the beam 27, so the roller peripheriesprovide a large number of independent supports for the part. Thefriction from these rollers is negligible, therefore the part remainsin, or attains, its free state, without internal stresses, throughoutthe loading and measurement process.

Other forms and arrangements of rollers can be used. For example, therollers can be a single set, each having a large convex peripheralconfiguration, or a larger number of rows of smaller rollers can beused. In an actual embodiment, three rows of rollers having a diameterof one inch, and with their centers spaced apart 9/16 of an inch. Therows extend along a cradle beam twenty feet in length.

Thus, it can be characterized that the extruded part is limp within thecradle, and the extruded part to be measured is placed and held bygravity, cradled in a semi-circular arrangement (see FIG. 4) and willstraighten as it settles under its own weight. Any tension orcompression forces temporarily created in the part during handling willbe relieved or dissipated, since each roller can move independently ofthe others, and each provides an incremental support of the part over avery short portion of its total length. The semi-circular cradle devicewill accommodate many different cross-sections of extruded seal.

The fixture includes a stainless steel scale 30 supported on a U-shapedmember 32 which is fastened to, and runs the length of leg 27B of beam27, the scale being used as a means of acquiring the lengthmeasurements. The zero point of the scale aligned with an end stop 34 atthe head end of the fixture. A floating end stop 35 (see FIGS. 5 and 6)with an integral pointer 36 rides in and along the part cradle, beingcylindrical in shape and simply slidably supported on rollers 20, Thisstop is used by rolling it against the free end of the part to indicatethe part length measurement via an arm extending toward scale 30.

While the method herein described, and the form of apparatus forcarrying this method into effect, constitute preferred embodiments ofthis invention, it is to be understood that the invention is not limitedto this precise method and form of apparatus, and that changes may bemade in either without departing from the scope of the invention, whichis defined in the appended claims.

What is claimed is:
 1. A fixture for measuring the length of longflexible extruded parts of different cross-sections, said parts beingformed of foam rubber and the like material and being incapable ofself-support in a straight line, comprisingan elongated cradle includingan upwardly open trough, a plurality of rollers having rims of likediameter arranged with said rims aligned seriatim in said trough topresent a series of support surfaces arranged in a line, support shaftsfor said rollers extending through the axis of rotation of thecorresponding rollers, said shafts extending parallel to each other andtransversely of said trough and being spaced apart a distance slightlygreater than the diameter of said rollers whereby the circumferentialrim surfaces of said rollers facing upward in said cradle provide a partsupport of discontinued segments of said rollers extending at least thefull length of the parts placed thereon, and localized tension andcompression in the part will dissipate due to the part being supportedindependently at relatively closely spaced increments along the lengthof the part, a scale attached to and extending along said trough, an endstop at one end of said trough for indexing a part placed thereon, and afloating stop movable along said rollers into engagement with a free endof a part and cooperating with said scale to indicate the length of apart.
 2. A fixture as defined in claim 1, further comprisingsaid troughbeing formed by a beam having an upwardly open top, a bottom, andopposed sides, said rollers being supported in alignment along said beamfrom the bottom and sides thereof into at least three rows of alignedroller supports for confining an elongated flexible part therein.
 3. Amethod of measuring length of long flexible extruded parts which areincapable of self-support in a straight line, comprisingsupporting thepart in a substantially straight horizontal position at independentlocations closely spaced lengthwise of the part, each support locationbeing provided by a freely rotatable roller aligned along a cradle withthe axes of the rollers parallel and each roller being independentlymovable with respect to adjacent rim surfaces of the part to allow thepart to expand or contract locally due to release of tension orcompression localized in the part, then measuring the length of therelaxed part.